SUGGESTIONS 


FOR   OBSERVING   THE 


TOTAL  ECLIPSE  OF  THE  SUN 


ON 


JANUARY  1,  1889. 


BY 

EDWARD  S.  JiOLDEN,  LL.D., 

Director  of  the  Lick  Observatory. 


PRINTED  BY  AUTHORITY  OF  THE  REGENTS  OF  THE  UNIVERSITY 
OF  CALIFORNIA.  . 


SACRAMENTO: 

STATE    OFFICE,   :    :    :    :    J.  D.  YOUNG,   SUPT.  STATE    PRINTING. 
1888. 


FT 

27  1G33 


I 


SUGGESTIONS 


FOR  OBSERVING  THE 


TOTAL  ECLIPSE  OF  THE  SUN 


ON 


JANUARY  1,  1889, 


BY 

EDWARD  S.  HOLDEN,  LL.D., 

Director  of  the  Eick  Observatory. 


PRINTED  BY  AUTHORITY  OF  THE  REGENTS  OF  THE  UNIVERSITY 
OF  CALIFORNIA. 


SACRAMENTO: 

STATE   OFFICE,  :    :    :    :   J.  D.  YOUNG,   SUPT.  STATE   PRINTING. 
1888. 


INTRODUCTORY  NOTE. 


The  following  brief  suggestions  in  regard  to  observing  the 
total  solar  eclipse  of  January  I,  1889,  have  been  compiled 
from  various  sources,  in  the  belief  that  they  may  be  of  use  to 
intending  observers. 

It  is  hoped  that  the  Lick  Observatory  may  find  means  to 
print  the  results  of  observations  made  by  its  astronomers  in  the 
field,  and  at  Mount  Hamilton.  Any  valuable  observations 
made  by  other  observers,  and  promptly  communicated  to  the 
Observatory,  will  be  included  in  such  a  publication.  Corre- 
spondence on  this  and  other  subjects  relating  to  the  eclipse 
should  be  addressed  to  the  Director  of  the  Lick  Observatory, 
Mount  Hamilton,  San  Jose,  California. 

1888,  September  17. 


SUGGESTIONS  TO  OBSERVERS. 


PHENOMENA  OF  TOTAL  ECLIPSES. — The  beginning  of  a 
total  solar  eclipse  is  marked  simply  by  the  small  black  notch 
made  in  the  luminous  disc  of  the  sun  by  the  advancing  edge 
or  limb  of  the  moon.  This  always  occurs  on  the  western  half 
of  the  sun,  as  the  moon  moves  from  west  to  east  in  its  orbit. 
An  hour  or  more  must  elapse  before  the  moon  has  advanced 
sufficiently  far  in  its  orbit  to  cover  the  sun's  disc.  During  this 
time  the  disc  of  the  sun  is  gradually  hidden  until  it  becomes 
a  thin  crescent. 

The  actual  amount  of  the  sun's  light  may  be  diminished  to 
two  thirds  or  three  fourths  of  its  ordinary  amount  without  its 
being  strikingly  perceptible  to  the  eye.  What  is  first  noticed 
is  the  change  which  takes  place  in  the  color  of  the  surrounding 
landscape,  which  begins  to  wear  a  ruddy  aspect.  This  grows 
more  and  more  pronounced,  and  gives  to  the  adjacent  country 
that  weird  effect  which  lends  so  much  to  the  impressiveness  of 
a  total  eclipse.  The  color  changes  because  the  sun's  atmos- 
phere absorbs  a  larger  proportion  of  the  blue  rays  than  of  the 
red.  As  this  absorption  is  dependent  on  the  thickness  of  the 
solar  atmosphere  through  which  the  rays  must  pass,  it  is  plain 
that  just  before  the  sun  is  totally  covered,  the  rays  by  which 
we  see  it  will  be  redder  than  ordinary  sunlight,  since  they 
come  from  points  near  the  sun's  limb  and  must  pass  through 
the  greatest  thickness  of  the  sun's  atmosphere. 

The  color  of  the  light  becomes  more  and  more  lurid  up  to 
the  moment  when  the  sun  has  nearly  disappeared.  If  the 
spectator  is  upon  the  top  of  a  high  mountain,  he  can  then 
begin  to  see  the  moon's  shadow  rushing  towards  him  at  the 
rate  of  about  a  mile  in  a  second.  Just  as  the  shadow  reaches 

851037 


4  Suggestions  for  Observing 

him  there  is  a  sudden  increase  of  darkness;  the  brighter  stars 
begin  to  shine  in  the  dark  lurid  sky,  the  thin  crescent  of  the 
sun  breaks  up  into  small  points  or  dots  of  light,  which  sud- 
denly disappear,  and  the  moon  itself,  an  intensely  black  ball, 
appears  to  hang  isolated  in  the  heavens. 

An  instant  afterward  the  sun's  corona  is  seen  surrounding  the 
black  disc  of  the  moon  with  a  soft  effulgence  quite  different 
from  any  other  light  known  to  us.  Near  the  moon's  limb  it  is 
intensely  bright,  and  to  the  naked  eye  uniform  in  structure; 
5'  or  10'  from  the  limb  this  inner  corona  has  a  boundary  more 
or  less  defined,  and  from  this  extend  streamers  and  wings  of 
fainter  and  more  nebulous  light.  These  are  of  various  shapes, 
sizes,  and  brilliancy.  No  two  solar  eclipses  yet  observed  have 
been  alike  in  this  respect.  These  appearances,  though  change- 
able, do  not  appear  to  change  in  the  time  the  moon's  shadow 
requires  to  pass  from  the  first  contact  with  the  earth  to  its  last. 

Superposed  upon  these  wings  may  be  seen  (sometimes  with 
the  naked  eye)  the  red  flames,  or  protuberances,  which  were 
first  discovered  during  a  total  eclipse.  These  need  not  be 
more  closely  described  here,  as  they  can  now  be  studied  at 
any  time  by  the  aid  of  a  spectroscope. 

The  total  phase  of  a  solar  eclipse  lasts  for  a  few  minutes 
(never  more  than  six  or  seven,  and  about  two  minutes  only  at 
the  eclipse  of  January  i,  1889),  and  during  this  time,  as  the 
eye  becomes  more  and  more  accustomed  to  the  faint  light,  the 
outer  corona  is  seen  to  stretch  further  and  further  away  from 
the  sun's  limb.  At  the  eclipse  of  1878,  July  29,  it  was  seen 
to  extend  more  than  6°  (about  9,000,000  miles)  from  the  sun's 
limb.  Just  before  the  end  of  the  total  phase  there  is  a  sudden 
increase  of  the  brightness  of  the  sky,  due  to  the  increased 
illumination  of  the  earth's  atmosphere  near  the  observer,  and 
in  a  moment  more  the  sun's  rays  are  again  visible,  seemingly 
as  bright  as  ever.  From  the  end  of  totality  till  the  last  con- 
tact the  phenomena  of  the  first  half  of  the  eclipse  are  repeated 
in  inverse  order. 


The  Eclipse  of  January  1,  1889. 


TELESCOPIC  APPEARANCE  OF  THE  CORONA. — Such  are  the 
appearances  to  the  naked  eye.  The  corona,  as  seen  through 
the  telescope,  is,  however,  of  a  very  complicated  structure. 
The  inner  corona  is  usually  composed  of  bright  striae  or  fila- 
ments separated  by  darker  bands,  and  some  of  these  latter 
are  occasionally  seen  to  be  almost  totally  black.  The  appear- 
ances are  extremely  irregular,  but  they  are  often  as  if  the 
inner  corona  were  made  up  of  brushes  of  light  on  a  darker 
background. 

The  corona  and  red  prominences  are  solar  appendages. 

It  was  formerly  doubtful  whether  the  corona  was  an  atmos- 
phere belonging  to  the  sun  or  the  moon.  At  the  eclipse  of 
1860  it  was  proved  by  measurements  that  the  red  prominences 
belonged  to  the  sun  and  not  to  the  moon,  since  the  moon 
gradually  covered  them  by  its  motion,  they  remaining  attached 
to  the  sun.  The  corona  has  also  since  been  .shown  to  be  a 
solar  appendage. 

LICK  OBSERVATORY  TIME-SIGNALS. 

On  the  29th,  3Oth,  and  3ist  of  December,  and  on  the  ist 
and  2d  of  January,  the  time-signals  of  the  Lick  Observatory 
will  be  sent  to  (nearly)  every  railway  station  in  California  auto- 
matically from  a  standard  mean-time  clock.  Observers  should 
compare  their  watches  with  the  beats  of  the  sounder  at  noon 
in  the  nearest  railway  station,  when  possible.  These  signals 
will  be  similar  to  the  regular  noon  Time-Signals  of  this  Observ- 
atory, which  furnishes  the  official  time  to  the  Southern  Pacific 
Company.  These  signals  commence  with  a  warning  "rattle" 
between  11:56  and  11:57  °f  Pacific  Standard  Time,  there  is 
then  a  pause  of  one  minute  (during  which  the  wires  are  cleared 
for  the  transmission  of  the  "noon-signal"),  and  the  first  beat 
of  the  clock,  which  will  be  heard  at  the  distant  telegraph  sta- 
tion is  1 1  hr.  58  min.  oo  sec.  of  P.  S.  T.  Thereafter,  the  clock 
will  beat  every  even  second — leaving  out  the  58th  second — the 
first  beat  after  this  short  pause  is  11:59:0,  and  the  clock  will 


Suggestions  for  Observing 


continue  to  beat  the  even  seconds  until  11:59:50,  when  there 
will  be  a  pause  of  10  seconds,  and  the  last  beat  heard  will  be 
12:00:00,  or  NOON  of  Pacific  Standard  Time  (equal  to  8:00:00 
of  Greenwich  Mean  Time). 

If  it  is  not  practicable  to  visit  one  of  the  railway  telegraph 
stations  at  noon,  for  these  signals,  the  beats  of  the  Lick  Observ- 
atory clock  may  be  heard  by  telephone  at  any  time  of  the  day, 
following  out  the  programme  given  below. 

To  hear  the  beats  of  the  Lick  Observatory  Standard  Clock, 
call  the  Central  Office,  and  ask  that  the  San  Jose  operator 
put  on  the  Lick  Observatory  clock  signal.  When  this  rs  done, 
the  beats  of  the  Lick  Observatory  clock  will  be  heard  every 
two  seconds.  At  the  end  of  every  minute  the  58th  second  is 
omitted.  At  the  end  of  every  5th  minute  (o,  5,  10,  15,  20,  25, 
30,  35,  40,  45,  50,  55,  60)  the  52d,  54th,  56th,  and  58th  seconds 
are  omitted. 

To  set  your  watch  right :  Get  the  beats  of  the  Lick  Observ- 
atory clock  in  your  telephone,  and  hold  your  watch  where  you 
can  see  the  second  hand;  listen  to  the  beats,  which  are  heard 
every  two  seconds,  until  a  pause  of  more  than  two  seconds 
comes;  the  first  dot  after  such  a  pause  begins  some  minute. 
If  the  pause  is  ten  seconds  long,  the  minute  is  one  of  the  num- 
bered minutes  of  your  watch-dial. 

APPROXIMATE  TIMES  OF  BEGINNING  AND  ENDING  OF  THE 
TOTAL  PHASE. 

I  have  asked  Professor  SCHAEBERLE,  of  the  Lick  Observ- 
atory, to  compute  the  approximate  Pacific  Standard  Times 
of  the  beginning  and  ending  of  the  total  phase,  and  his  results 
are  exhibited  in  the  following  table.  They  will  serve  a  useful 
purpose  in  enabling  intending  observers  to  select  a  suitable 
station.  The  latitudes  and  longitudes  of  the  various  stations 
were  taken  from  a  tracing  of  WHITNEY'S  map  of  California, 
made  by  Mr.  HlLL,  of  this  Observatory  (a  copy  of  a  part  of 
which  accompanies  this  pamphlet),  and  these  positions  may 


The  Eclipse  of  January  1,  1889. 


7 


be  erroneous  by  considerable  amounts  on  account  of  errors  in 
the  map.    Hence  the  computed  times  are  merely  approximate. 


PLACE. 

Total  Eclipse. 

Dura- 
tion. 

Begins. 

Ends. 

Mendocino          ....                 

h 

m.       s. 

45  3i 

45    2 
44  59 
46  44 

46  31 
46  48 
48  15 
47  4i 
47  46 
47  43 
47  56 
47  52 
47  59 
48  10 
48  02 
48  23 
48  19 
48  32 
49  13 
49  17 
48  59 
50  25 
50  43 
49  53 

50    21 
SO   24 

47  14 
47     5 
47     i 
48  32 
48  33 
48  51 
48  52 
49  40 

49  49 
49  33 
49  58 
49  24 
49  12 
50     5 
49  16 
5°  17 
5°  16 
50  35 
50  54 
50  55 
5i     i 
5i  47 

52    12 

5i  53 
52  16 
51  50 

D 

] 

2 

C 
] 
1 
] 

1.       8. 

43 
-  03 

\   02 
48 
\   02 
5    03 

>  37 
[  59 
i  03 

[  50 

I   02 
[    32 
[     13 

[  55 
H 
54 
57 
03 
4i 
38 
02 

22 

29 
OO 

55 
26 

Punta  Arenas                                              .... 

Ukiah                  

Cloverdale            

Lakeport                   .    .                                       .... 

Lick  Observatory  Station     

Calistoga    ...      .             

Willows          

Norman  

Orland    

Maxwell         ...          .... 

Corning 

Tehama        

Colusa  Junction 

Sesma 

Colusa 

Chico          

Nelson              

Yuba 

Marysville  

Oroville  ... 

Grass  Valley  

Nevada  City  

Ouincy 

Dow  n  ieville 

Susan  ville            

Approximate  times  of  First   and   Last  Contacts.     (Pacific 
Standard  Time.) 


1st  Contact. 

4th  Contact. 

At  the  Lick  Observatory 

nh 

24™     58s 

•2h          Qm          •26s 

At  Professor  Davidson's  Observatory,  San 

Francisco  

0 

23         8 

3         8         56 

At  the  Students'  Observatory,  Berkeley  .... 

0 

23        31 

398 

At  the  Lick  Observatory  field  station  

0 

22           19 

3         7         17 

The  point  of  first  contact  will  be  about  91°  from  the  north  point  of  the  sun's 
limb  measured  towards  the  west. 

NOTE. — In  telescopic  observations  of  the  first  contact,  care  should  be  taken  to 
employ  an  eye-piece  with  a  field  of  view  of  at  least  1 5'  to  20'  of  arc.  The  second 
and  third  contacts  should  be  observed  with  high  powers  and  small  fields ;  and  the 
fourth  contact  may  be  so  observed,  though  it  is  probably  better  to  employ  the  same 
eye-piece  for  observations  of  both  the  first  and  fourth  contacts. 


8  Suggestions  for  Observing 


GENERAL  REMARKS. 

The  phenomena  of  a  total  eclipse  are  so  various,  so  start- 
ling, so  impressive,  and  so  indescribably  novel  and  fascinating 
that  those  engaged  in  observation  will  do  well  to  confine  their 
attention  to  that  special  portion  which  they  can  best  observe, 
leaving  the  other  portions  to  other  members  of  the  party. 
Only  in  this  way  can  a  definite  result  be  certainly  attained. 

During  the  observation  of  an  eclipse,  it  is  necessary  that 
quiet  and  stillness  should  be  maintained.  A  whispering,  mur- 
muring crowd,  much  more  a  noisy,  talkative  one,  may  seri- 
ously impair  observations,  or  even  occasion  their  total  loss. 
What  can  be  seen  with  the  unaided  eye  can  be  as  well  seen 
many  miles  away  as  in  the  immediate  vicinity  of  those  who 
are  provided  with  instruments  for  precise  observations.  No 
visitors  will  be  admitted  to  the  Lick  Observatory  on  the  day  of 
the  eclipse. 

The  nature  and  character  of  the  instruments  employed 
should  be  stated  by  each  observer  in  his  report,  together  with 
any  circumstance  which  may  affect  the  reliability  or  value  of 
the  results.  Thus,  in  the  case  of  a  telescope,  the  aperture 
used,  focal  length  and  magnifying  power,  and  the  shade-glasses 
employed,  should  be  recorded;  also,  during  the  observations, 
the  transition  of  the  eye  of  the  observer  from  light  to  obscurity, 
or  the  reverse,  the  deposit  of  dew  on  the  glasses,  or  any  change 
or  defect  in  adjustment.  Notes  at  the  time  should  be  brief 
and  condensed,  but  written  out  at  length  immediately  after- 
wards, and  without  conference  with  others.  The  results  of 
such  a  conference  should  be  given  separately. 

CHOICE  OF  OBSERVING  STATION. 

A  position  should  be  selected  which  is  free  from  the  annoy- 
ances of  wind,  dust,  and  dazzling  reflection  from  water,  and 
the  noise  and  din  of  a  thoroughfare;  which  affords  a  clear 
view  of  the  portion  of  the  heavens  to  which  the  attention  will 


The  Eclipse  of  January  1,  1889.  9 

be  directed,  and  an  unobstructed  meridian,  if  precise  observa- 
tions for  time  are  contemplated ;  and  elevated  above  the  ordi- 
nary range  of  fogs,  where  fogs  are  to  be  apprehended. 

The  place  should  be  noted  and  described,  and  its  bearing 
and  distance  from  some  public  building  or  prominent  land- 
mark should  be  determined.  It  should  be  resorted  to  one  or 
more  days  in  advance,  in  order  to  have  everything  in  readiness 
and  suitably  arranged. 

I.     OBSERVATIONS  OF  THE  CONTACTS. 

These  consist  in  observing  the  instants  of  beginning  and 
end  both  of  the  eclipse  and  of  the  total  phase,  together  with 
the  positions  of  the  points  of  contact,  and  serve  to  give  a  pre- 
cise determination  of  the  moon's  place. 

It  is  desirable  that  the  beginning  and  end  of  the  eclipse 
should  be  carefully  observed  at  all  fixed  observatories  within 
its  limits.  The  beginning  and  end  of  the  total  phase  can  only 
be  observed  within  the  belt  of  totality. 

The  value  of  such  observations  depends  on  the  precision 
with  which  the  instant  of  contact  is  appreciated  and  its  time 
recorded,  and  the  exactness  with  which  the  correction  of  the 
chronometer  and  the  longitude  and  latitude  of  the  place  are 
determined.  Where  good  observations  have  been  made,  meas- 
ures may  be  taken  subsequently  for  fixing  the  geographical 
position. 

II.     OBSERVATIONS   NEAR  THE   LIMITS  OF  THE 

SHADOW. 

The  intelligent  inhabitants  of  towns  near  the  edge  of  the 
belt  'of  totality  may  furnish  observations  by  which  the  limits 
can  be  accurately  determined  by  simply  noting  how  many  sec- 
onds the  sun  is  wholly  obscured  by  the  moon.  The  following 
directions  for  doing  this  are  mostly  taken  from  a  circular  issued 
by  the  Naval  Observatory  asking  for  observations  of  the  eclipse 
of  August  7,  1869. 


10  Suggestions  for  Observing 

INSTRUMENTS:  The  only  indispensable  instrument  is  a 
good  watch,  provided  with  a  seconds-hand,  and  having  a 
white  face.  It  may  be  well  to  provide  a  lighted  lantern  for 
use  in  case  of  necessity.  The  minute-hand  of  the  watch  should 
be  carefully  set  so  as  to  be  on  the  exact  minute  when  the  sec- 
onds-hand is  at  6os.  This  being  done  it  is  no  matter  how  far 
wrong  the  watch  may  be. 

A  good  auxiliary  will  be  a  common  spy-glass  lashed  to  a 
round  post  so  as  to  be  steady  enough  to  give  an  easy  view  of 
the  sun.  To  lessen  the  brilliancy  of  the  sun,  cover  the  object 
glass  with  a  pasteboard,  tin,  or  wooden  cap  having  a  round  hole 
three  fourths  of  an  inch  in  diameter  cut  in  its  center. 

The  spy-glass  will  be  worse  than  useless  unless  one  is  accus- 
tomed to  its  use,  and  has  it  fastened  so  as  to  be  steady. 

An  opera-glass  held  in  the  hand  may  also  serve  a  good  pur- 
pose. A  smoked  glass  should  also  be  prepared,  but  one  part 
of  the  glass  should  be  smoked  very  lightly  so  that  it  can  be 
used  should  the  day  be  cloudy. 

Arrangement  for  Observation. — Each  observation  should  be 
made  by  a  party  of  three  persons.  Only  one  instrument  of 
each  kind — watch,  glass,  etc. — is  needed  by  a  party.  A  station 
should  be  selected  where  they  will  be  free  from  all  interruption, 
either  in  the  open  air  or  at  an  open  window,  facing  south  or 
southwest.  Be  sure  that  the  sun  can  be  seen  from  your  station 
at  1 130  P.M.,  by  a  trial  one  or  two  days  before  the  eclipse.  One, 
at  least,  of  the  party  must  have  a  pencil  and  note  book  at  hand 
to  record  the  time. 

Tlie  Observation. — When  the  visible  part  of  the  sun  is  reduced 
to  the  narrowest  crescent,  the  holder  of  the  watch,  keeping  his 
eye  on  the  face,  will  begin  to  count  the  seconds  aloud ;  the 
holder  of  the  smoked  glass,  with  or  without  the  spy-glass,  will 
watch  for  the  last  ray  of  true  sunlight,  being  careful  to  look 
through  the  brightest  part  of  the  glass  the  eye  will  bear  with- 
out inconvenience;  and  the  third  observer,  if  there  be  one,  will 
look  for  the  disappearance  of  sunlight  with  the  naked  eye,  and 
stand  ready  with  pencil  and  paper  to  record  the  time.  When 


The  Eclipse  of  January  1,  1889.  11 

the  last  ray  of  the  sun  has  disappeared,  the  observer  with  the 
glass  will  call  "time,"  and  the  exact  second  at  which  the  call 
was  given  must  be  immediately  written  down.  The  minute 
also  must  be  carefully  noted  and  immediately  recorded.  It  is 
best  to  record  the  seconds  first,  and  then  the  minutes.  The 
observers  will  then  await  the  return  of  sunlight,  the  count  of 
seconds  being  kept  up.  The  first  flash  of  true  sunlight  will 
seem  to  burst  out  suddenly,  and  the  minute  and  second  of  its 
appearance  must  be  immediately  recorded  with  the  same  care 
as  the  time  of  disappearance.  The  difference  of  the  two  times 
gives  the  duration  of  totality. 

Valuable  observations  of  the  duration  of  totality  can  be  made 
at  any  points  at  or  near  the  limits  of  the  line  of  totality,  in  par- 
ticular at  or  near  the  points  named  below.  Observers  should 
remember  that  the  fact  that  the  eclipse  was  not  total  at  their 
stations  is  just  as  important  as  the  other  fact  that  the  duration 
of  totality  was  one,  two,  or  three  seconds.  If  these  observations 
are  carefully  made,  and  promptly  communicated  to  the  Lick 
Observatory,  they  will  serve  a  useful  purpose. 

Northern  Limit. 

Westport,  Mendocino  County. 
Kibesilla,  Mendocino  County. 
Tilly,  Mendocino  County. 
Cahto,  Mendocino  County. 
Laytonville,  Mendocino  County. 
Covelo,  Mendocino  County. 
Camp  Wright,  Mendocino  County. 
Red  Bluff,  Tehama  County. 
Lyonsville,  Tehama  County. 

Southern  Limit. 

Duncan's  Mills,  Sonoma  County. 
Occidental,  Sonoma  County. 
Windsor,  Sonoma  County. 
Mark  West,  Sonoma  County. 


12.  Suggestions  for  Observing 

America,  Sonoma  County. 
Calistoga,  Napa  County. 
Pope  Valley,  Napa  County. 
Brooks,  Yolo  County. 
Capay,  Yolo  County. 
Dunnigan,  Yolo  County. 
Black's,  Yolo  County. 
Grafton,  Yolo  County. 
Wheatland,  Yuba  County. 
Spencerville,  Nevada  County. 
You  Bet,  Nevada  County. 
Lowell  Hill,  Nevada  County. 
Donner,  Nevada  County. 
Alta,  Placer  County. 
Dutch  Flat,  Placer  County. 
Gold  Run,  Placer  County. 
Blue  Canyon,  Placer  County. 
Emigrant  Gap,  Placer  County. 
Cisco,  Placer  County. 

Special  Precautions. — In  appreciating  the  beginning  of  total- 
ity there  is  danger  of  error  from  two  sources.  The  first  is  that 
the  sun's  crescent  may  become  so  narrow  as  to  become  invisi- 
ble through  the  smoked  glass,  if  this  be  too  dark,  several  sec- 
onds before  it  is  really  all  covered,  and  thus  the  observer  may 
call  the  "time"  too  soon.  Such  a  mistake  may  be  detected 
and  corrected  by  the  third  observer  looking  on  with  the  naked 
eye,  if  the  following  circumstances  be  attended  to: 

The  beginning  of  total  eclipse  is  marked  by  a  very  rapid 
increase  of  the  darkness,  caused  by  the  advent  of  the  moon's 
shadow.  If,  then,  the  darkness  increases  more  rapidly  after 
time  is  called  than  it  did  before,  time  was  called  too  soon,  and 
must  be  repeated.  The  other  danger  is  of  the  opposite  kind, 
and  should  be  equally  avoided.  It  is  that  the  light  of  the 
brilliant  rose-colored  protuberances  which  surround  the  dark 
body  of  the  moon  during  the  total  eclipse  may  be  mistaken 


The  Eclipse  of  January  1,  1889.  13 

for  sunlight,  and  thus  the  critical  moment  be  suffered  to  pass. 
In  this  case  each  observer  must  determine  separately  the 
exact  second  at  which  it  ceased  to  grow  darker,  and  if  they 
agree  within  one  or  two  seconds,  the  time  may  be  supposed 
correct,  and  each  one's  estimate  may  be  written  down  sepa- 
rately. The  observer  with  the  smoked  glass  will  be  most 
liable  to  the  first  of  these  mistakes;  the  naked-eye  observer  to 
the  last. 

The  return  of  sunlight  will  also  be  preceded  by  a  reddish 
glow  on  the  border  of  the  dark  moon,  which  must  not  be  mis- 
taken for  the  sun.  Indeed,  if  the  observer  be  near  the  edge 
of  the  shadow,  it  is  probable  that  this  red  glow,  which  comes 
from  the  hydrogen  atmosphere  of  the  sun,  may  be  visible  dur- 
ing the  whole  time  of  totality. 

All  the  recorded  times,  with  an  estimate  of  the  uncertainties 
to  which  the  observers  think  they  are  liable,  and  a  statement 
of  the  place  where  made,  giving  distance  in  miles  and  direc- 
tion from  the  Court  House,  if  it  be  a  county  town,  and  from 
the  railroad  station,  if  a  railroad  pass  through,  referring  also  to 
the  United  States  land  surveys,  should  be  immediately  certi- 
fied by  the  signatures  of  all  three  observers,  and  forwarded  to 
the  Lick  Observatory. 

It  is  particularly  requested  that  each  party  send  off  its  report 
before  comparing  notes  with  any  other  party;  also,  that  the 
original  pencil  record,  however  imperfect,  accompany  the  re- 
port; and  it  is  hoped  that  many  persons  will  take  the  pains  to 
make  these  simple  yet  valuable  observations. 

III.     SPECTROSCOPIC  OBSERVATIONS. 

These  are  of  special  importance  during  the  total  phase.  A 
direct-vision  spectroscope,  attached  to  a  telescope  of  moderate 
power,  is  recommended  as  most  convenient  and  most  readily 
manipulated.  Familiarity  with  the  most  prominent  lines  of 
the  solar  spectrum  is  an  essential  preparation.  An  assistant 
should  be  trained  to  direct  the  telescope  by  the  finder.  The 


14  Suggestions  fcr  Observing 

spectra  of  various  portions  of  the  corona  deserve  careful  exam 
ination.     The  position   of  the  part  examined,  and  the  time, 
should  be  noted.     Where  there  are  several  observers,  it  will  be 
better  for  each  to  confine  his  attention  to  a  designated  portion 
rather  than  to  attempt  to  observe  the  whole. 

IV.     METEOROLOGICAL     OBSERVATIONS. 

These  include  the  ordinary  record  of  the  barometer,  dry 
and  wet  bulb  thermometers,  winds,  clouds,  and  other  condi- 
tions of  the  atmosphere.  Near,  and  during  the  total  phase, 
the  changes  of  the  thermometer  and  hygrometer,  formation  of 
clouds,  or  fog,  or  dew,  or  other  atmospheric  variations,  should 
be  especially  noted. 

V.     DRAWINGS    OF    THE    CORONA. 

Careful  drawings  of  the  corona  may  be  of  value.  The  ob- 
server should  provide  himself  with  a  tablet  to  draw  upon,  and 
a  couple  of  soft  pencils  (No.  2,  or  BB),  sharpened  at  both  ends. 
In  the  middle  of  the  paper  draw  two  lines  at  right  angles,  and 
mark  their  extremities  top,  bottom,  right,  left.  With  their  inter- 
section as  a  centre  and  a  radius  of  one  inch  draw  a  circle  to 
represent  the  moon.  During  totality  fill  in  the  details  deliber- 
ately and  conscientiously.  A  careful  drawing  half  finished  is 
better  than  one  covering  all  the  region  which  is  done  in  haste. 
Send  the  original  drawing  with  notes  to  the  Lick  Observatory 
for  comparison  with  others  of  the  same  kind. 

A  really  important  observation  can  be  made  in  the  follow- 
ing way:  Place  a  circle  of  wood,  or  iron,  12  inches  in  diame- 
ter, near  the  top  of  a  telegraph  or  other  pole,  and  place  the 
eye  at  about  57  feet  from  the  disc,  so  that  at  the  time  of  total- 
ity the  center  of  the  disc  will  cover  the  center  of  the  sun. 
The  position  for  the  eye  can  be  approximately  determined  on 
the  days  immediately  preceding  the  eclipse,  and  a  stake  can 
be  firmly  driven,  over  the  very  top  of  which  the  observer  is  to 


The  Eclipse  of  January  1, .  1889.  IB 

look  at  the  totally  eclipsed  sun.  The  sun,  and  the  inner  (and 
brighter)  corona  will  be  hidden,  and  the  eye  can  then  follow 
the  outer  and  fainter  portions  with  ease,  and  estimate  their 
directions  (angles  with  the  vertical  post)  and  their  lengths  (in 
diameters  of  the  disc).  The  eye  should  be  kept  in  darkness 
up  to  the  beginning  of  the  total  phase. 

VI.     SPECIAL     PHENOMENA. 

(Near  the  times  of  beginning  and  end  of  the  eclipse.) 

(i).  Visibility  of  the  limb  of  the  moon  before  it  touches 
and  after  it  leaves  the  sun,  and  the  time  and  distance  at  which 
it  is  noticed. 

(2).  Apparent  agitation  of  the  sun's  limb  near  the  point  of 
contact  immediately  before  and  after  the  eclipse. 

(3).  Whether  the  contacts  are  instantaneous  and  well  de- 
fined, or  whether  there  are  apparent  adhesions  and  distortions, 
formation  of  beads,  or  portions  of  the  moon's  limb  separated 
by  dark  lines,  or  other  irregularities  of  outline. 

(During  the  progress  of  the  eclipse.) 

(4).  Projection  of  the  moon  beyond  the  sun;  the  time  and 
extent  to  be  noted. 

(5).  Irregularities  of  the  moon's  limb.  Distortions  of  the 
solar  cusps,  their  color,  and  shading. 

(7).  Bright  band  bordering  the  the  moon's  edge;  color  of 
the  glass  screen  through  which  the  moon  is  best  seen. 

(8).  Flashes  or  coruscations  of  light  across  the  moon. 

(9).  Any  peculiarities  in  the  illumination  and  color  of  the 
moon's  disc  or  any  portion  of  it ;  spots  which  may  be  visible. 

(10).  Any  peculiarity  in  the  appearance  and  color  of  the 
solar  spots,  especially  near  the  edge  of  the  moon. 

(Near  the  instants  of  total  immersion  and  of  emersion.) 

(11).  Rapid  change  of  the  last  visible  portion  of  the  sun,  or 
of  that  which  first  reappears;  a  separation  into  minute  parts, 
or  formation  of  Baily's  beads,  with  dark  lines  among  them. 


16  Suggestions  for  Observing 

(12).  Any  increased  brightness  of  the  moon's  edge,  and  when 
and  where  it  is  noticed. 

(13).  Flashes,  rays,  or  bright  points  as  the  sun  disappears  or 
reappears. 

(14).  The  approach  and  recession  of  the  shadow,  appearing 
on  the  ground  like  that  of  a  cloud,  should  be  watched  by  those 
who  are  not  occupied  with  other  observations;  and  any  pecu- 
liarities described,  as  for  instance,  whether  its  appearance  and 
motion  are  uniform,  or  if  dark  stripes  appear  flitting  across 
the  landscape;  if  these  are  seen  their  distance  apart,  width, 
and  velocity  should  be  noted. 

(During  the  total  phase.) 

(15).  The  general  appearance  and  extent  of  the  corona; 
when  and  where  it  first  appears  and  disappears;  whether  uni- 
formly surrounding  the  moon's  disc,  or  brighter  and  more 
extensive  on  one  side,  especially  where  the  sun  has  just  disap- 
peared, or  is  about  reappearing;  its  color  in  different  portions; 
its  shading,  and  whether  separated  into  two  portions,  one 
brighter  and  shaded  uniformly,  the  other  radially  striated;  its 
changes. 

(16).  Prominences  or  protuberances  along  the  edge  of  the 
moon,  with  their  position,  form,  extent,  color,  and  any  other 
peculiarity;  also  their  formation,  growth,  and  any  other  changes. 
The  position  and  extent  should  be  noted  on  a  diagram  pre- 
viously prepared. 

(17).  Colors  of  the  clouds  or  fog,  and  especially  a  note  of 
the  changes  of  color. 

If  there  are  several  observers  with  telescopes,  it  is  desirable 
that  one  should  keep  the  whole  corona  in  view,  while  each  of 
the  others  confines  his  attention  to  some  designated  portion. 
Those  without  telescopes,  or  supplied  with  opera-glasses,  or 
spy-glasses,  should  also  note  the  appearance,  extent,  and  pecu- 
liarities of  the  corona,  as  it  appears  to  them. 

(18).  A  comet  may  possibly  be  seen  near  the  sun,  or  an 
aurora  be  visible. 


The  Eclipse  of  January  1,  1889.  17 


VII.  PHOTOGRAPHY. 

Photographs  of  the  corona  of  very  considerable  scientific 
value  can  be  made  with  the  apparatus  in  ordinary  use  by  photo- 
graphers. With  this  view,  the  camera  should  be  fitted  with  the 
largest  and  longest  focused  lens  at  the  operator's  disposal,  and 
then  should  be  most  carefully  focused  with  the  full  aperture, 
upon  some  distant  object  placed  in  the  middle  of  the  ground 
glass.  The  image  will  be  well  defined  over  a  small  space  in 
the  center  of  the  ground  glass  only,  but  that  is  of  no  conse- 
quence, Two  or  three  minutes  before  totality,  six  or  eight 
plates  should  be  in  readiness  for  immediate  use.  The  camera 
should  also  be  in  readiness,  directed  towards  the  sun,  and  held 
there  in  any  convenient  manner.  As  the  sun  will  be  at  a  con- 
siderable altitude,  the  ordinary  camera  stand  may  not  be  avail- 
able, but  with  a  little  ingenuity  some  rough  contrivance  can  be 
made  which  will  answer  the  purpose. 

The  camera  should  be  carefully  examined  beforehand  to  see 
if  it  is  light-tight,  by  covering  the  head  with  a  heavy,  thick 
black  cloth,  and  looking  into  the  camera  from  the  rear  with 
the  lens  in  place  and  cap  on,  and  also  from  the  front  with  the 
plate-holder  in  place  and  the  lens-front  removed.  This  should 
be  done  in  strong  sunlight,  and  the  camera  turned  in  every 
direction,  to  detect  any  pin-holes  in  the  bellows,  or  cracks  and 
leaks  in  the  woodwork,  and  especially  in  the  fitting  of  the 
plate-holder  and  the  sliding  front.  Very  few  new  cameras,  and 
still  fewer  old  ones,  are  absolutely  light-tight,  and  the  smallest 
quantity  of  outside  light,  admitted  in  this  way,  will  greatly  in- 
jure or  entirely  destroy  what  might  otherwise  be  a  perfect  neg- 
ative. 

All  the  holders  should  be  filled  and  laid  beside  the  camera, 
so  that  they  can  be  used  without  delay.  Then,  the  focus  of 
the  camera  remaining  as  it  was  when  adjusted  upon  the  distant 
object,  so  soon  as  totality  commences  and  the  operator  has 
assured  himself  that  the  image  of  the  corona  is  in  the  center 
2 


18%  Suggestions  for  Observing 

of  the  ground  glass,  he  should  insert  a  plate,  and  expose  it. 
The  ground  glass  should  next  be  replaced,  when,  owing  to  the 
diurnal  motion  of  the  earth,  it  will  be  seen  that  the  image  of 
the  corona  has  moved  away  from  the  center  of  the  field.  It 
should  then  be  put  back,  after  which  another  plate  should  be 
inserted  and  exposed;  and  this  routine  should  be  repeated  till 
the  totality  is  over,  when  the  plates  can  be  developed. 

If  the  camera  is  provided  with  any  one  of  the  simple  finders 
which  are  used  in  taking  instantaneous  views,  it  will  not  be 
necessary  to  examine  the  ground  glass  after  each  exposure, 
and  the  number  of  exposures  can  be  materially  increased. 
If  the  image  of  the  sun  is  in  the  center  of  the  field  of  the 
finder,  it  must  be  in  the  proper  place  on  the  plate.  With  a 
little  previous  attention  to  sighting  the  camera,  by  looking 
along  the  corners,  or  the  middle  of  the  upper  side,  any  given 
object  can  be  placed  sufficiently  near  the  center  of  the  plate. 
This  will  be  more  easily  done  with  simple  sights  attached  to 
the  camera,  and  adjusted  to  point  at  a  distant  object  when  it 
is  in  the  middle  of  the  plate. 

It  seems  to  be  preferable  not  to  give  definite  directions  for 
the  exposure-times  with  each  lens  and  plate  likely  to  be  used, 
but  rather  to  suggest  a  general  plan  of  work  and  to  leave  the 
details  to  the  individual  operator. 

Valuable  experience  can  be  had  by  photographing  light 
clouds  away  from  the  sun ;  or  near  the  sun,  when  it  is  obscured 
by  heavy  clouds;  or  just  after  sunset.  Several  exposures  of 
different  times  made  in  this  way  will  show  which  one  is  best 
suited  to  give  all  the  details  of  the  cloud  forms,  and  this 
exposure  (and  stop)  is  the  one  best  suited  for  photographs  of 
the  corona.  With  the  full  aperture  of  a  portrait-lens,  the  max- 
imum time  should  probably  not  exceed  five  seconds.  Some  of 
the  exposures  should  be  shorter,  down  to  the  quickest,  which 
can  be  made  with  the  cap  (something  near  half  a  second). 
One  plate  should  be  exposed  with  the  smallest  stop  and  the 
shortest  time  with  the  cap;  another  with  the  same  time  and  an 
intermediate  stop.  By  thus  varying  the  amount  of  light  re- 


The  Eclipse  of  January  1,  1859.  19 


ceived  by  the  plates,  there  is  more  likelihood  of  obtaining  a 
successful  picture,  showing  the  delicate  details  of  the  corona. 

The  photographer  should  make  the  preliminary  experiments 
here  recommended,  and  settle  on  a  programme  which  he  will 
follow  on  the  day  of  the  eclipse.  This  programme  should 
indicate  the  times  of  exposure  and  the  various  stops  to  be 
employed,  and  should  be  strictly  observed  if  the  day  of  the 
eclipse  is  clear.  If  the  day  is  foggy  or  overcast,  a  new  pro- 
gramme can  be  made.  In  any  event  the  data  named  should 
be  known  for  each  plate  exposed. 

Every  possible  care  should  be  used  to  avoid  fogging  the 
plates  in  placing  them  in  the  holders,  and  in  removing  them 
after  exposure,  as  well  as  in  the  earlier  stages  of  development. 
Only  a  feeble  red  light  should  be  used,  not  yellow  or  orange- 
green.  An  amount  of  fogging  which  would  be  imperceptible 
in  a  portrait  negative  will  utterly  spoil  what  might  otherwise 
have  been  a  satisfactory  negative  of  the  corona.  The  camera 
must  be  covered  with  a  black  cloth  whenever  the  slide  is  drawn, 
as  a  matter  of  course. 

Only  one  plate  at  a  time  should  be  developed,  and  the 
development  should  be  carried  on  very  slowly  and  cautiously 
to  determine  whether  the  plates  have  been  over-  or  under- 
exposed. Each  plate  should  be  fixed  and  examined  before 
the  development  of  another  is  commenced,  so  that  the  propor- 
tions of  the  developer  may  be  intelligently  varied,  if  necessary. 
In  any  case  the  development  should  not  be  hurried.  To  get 
the  best  results,  it  may  be  desirable  to  spend  half  an  hour  and 
upwards  on  each  plate.  With  a  short  time  and  a  strong  devel- 
oper, many  of  the  more  delicate  details  of  the  corona  are  cer- 
tain to  be  lost. 

On  account  of  the  motion  of  the  earth  while  the  plate  is 
being  exposed,  the  image  of  the  sun — or  rather  of  the  moon, 
which  covers  the  sun — will  be  a  little  blurred,  and  somewhat 
oval  in  shape;  and  to  prevent  disappointment,  it  must  be  borne 
in  mind  that  the  portrait  lenses  in  ordinary  use  have  such  short 
foci  that  they  can  give  but  very  small  pictures  of  the  moon. 


20  Suggestions  for  Ob se ruing1 

The  actual  size  in  inches  will  be  nearly  as  follows,  viz.:  With 
a  1-4  lens  (focus  about  5  inches),  0.04  inches;  with  a  1-2  lens 
(focus  about  8  inches),  0.07;  with  a  4-4  lens  (focus  about  10 
inches),  0.09;  and  with  an  extra  4-4  lens  (focus  about  1 6  inches), 
0.14.  The  diameter  of  the  extreme  outlying  portions  of  the 
corona  may  be  four  or  five  times  these  figures. 

It  is  hoped  that  photographers  making  pictures  in  this  man- 
ner will  send  the  original  negatives  to  the  Lick  Observatory; 
but  if  they  prefer  to  retain  them,  it  is  earnestly  requested  that 
they  will,  at  least,  send  positive  copies  on  glass.  Paper  prints 
are  useless  for  scientific  purposes. 

Each  plate  should  be  accompanied  by  a  statement  of  the 
kind  of  lens  used  in  its  production;  the  focal  distance  and 
aperture  of  that  lens;  the  diaphragm  employed;  the  kind  of 
plates  used ;  how  long  each  plate  was  exposed ;  and  the  means 
of  identifying  the  top.  The  latter  point  is  of  especial  impor- 
tance, and  the  upper  side  of  every  plate  must  be  carefully 
marked  when  it  is  put  in  the  holder,  because  the  character  of 
the  corona  is  such  that  without  this  precaution  it  may  be  impos- 
sible to  say  certainly  which  is  the  top  of  the  negative. 

Any  dry-plate,  with  which  the  photographer  is  acquainted, 
may  be  used,  but  preference  should  be  given,  other  things  being 
equal,  to  plates  giving  a  good  degree  of  intensity  and  con- 
trast in  the  images.  The  Seed  plate  (Sensitometer  Nos.  22  to 
26)  is  specially  well  adapted  to  this  work.  The  quick  Passa- 
vant  plates  are  also  suitable.  Of  course  the  rapidity  of  the 
plate  will  be  taken  into  account  in  giving  the  exposure. 

It  is  desirable,  though  by  no  means  essential,  that  every 
photographic  observer  should  be  provided  with  an  assistant  to 
record  for  him.  The  record  should  be  made  in  pencil,  on 
pieces  of  white  cardboard,  cut  to  a  convenient  size.  Each 
observer  should  be  provided  with  colored  or  smoked  glass  to 
view  the  sun  during  the  partial  phase,  so  that  he  may  not  be 
dazzled,  and  lose  precious  time  when  the  totality  comes  on. 

A  couple  of  photographs  of  the  sky,  taken  just  before  and 
again  after  totality,  will  be  interesting  to  show  the  position 
and  motion  of  the  clouds.  For  these  negatives  the  smallest 


The  Eclipse  of  January  1,  1889.  21 

stop  should  be  used,  and  the  time  made  as  short  as  possible, 
preferably  with  an  instantaneous  shutter. 

Plate-holders  of  the  form  that  fit  on  the  camera  back  from 
behind  and  catch,  rather  than  the  sliding  kind,  are  the  best,  as 
they  can  be  more  quickly  attached,  and  as  this  can  be  done 
with  less  danger  of  moving  the  instrument.  The  time  required 
to  insert  this  form  of  holder,  draw  the  slides,  push  them  back 
again,  remove  the  holder,  and  pick  up  another  one,  may  be 
taken  as  twelve  seconds,  or  six  seconds  to  a  plate.  It  can  be 
done  in  eight  seconds,  or  even  less,  but  it  is  better  to  take  more 
time  and  avoid  jarring  the  camera,  or  setting  it  in  vibration. 
Twelve  seconds  is  ample  time  for  an  8  by  10  holder,  and  no 
further  time  allowance  need  be  made.  The  slide  should  be 
drawn  as  far  as  a  chalk  mark  previously  placed  upon  it,  and 
then  pushed  back,  instead  of  removing  it  entirely  as  usual,  the 
camera  being  covered  with  a  dark  cloth.  By  this  means  a  full 
second  and  a  half  may  be  saved.  Of  course  the  projecting 
slide  must  be  protected  from  the  wind.  If  it  is  intended  to 
use  a  diaphragm  with  any  one  of  the  series  of  plates,  it  is 
better  to  take  this  plate  after  the  other  more  important  expos- 
ures have  been  made  without  diaphragms. 

When  great  accuracy  is  not  necessary,  the  simplest  way  to 
orient  the  pictures  is  to  take  a  couple  of  instantaneous  views 
of  the  sun  fifteen  or  twenty  minutes  before  totality,  and  about 
one  minute  apart,  upon  the  same  plate  (the  driving  clock  of 
the  telescope  being  stopped  in  the  meantime,  if  the  camera  is 
mounted  on  a  telescope  stand).  Take  two  more  about  the 
same  interval  after  totality.  The  mean  direction  of  motion  of 
the  cusps  on  these  two  plates  should  give  the  direction  of  the 
circle  of  declination  during  totality,  within  ten  or  fifteen 
minutes  of  arc. 

The  plates  should  be  numbered  with  a  soft  pencil  on  the 
corner  of  the  film  before  removing  them  from  the  plate-holder. 
The  intended  exposure  for  each  plate  should  be  indicated  in 
large  white  letters  on  the  slide.  The  black  tablet  slides  are 
very  convenient  for  this  purpose,  as  the  figures  may  be  chalked 
directly  upon  them. 


Photomount 

Pamphlet 

Binder 

Gaylord  Bros.,  Ii 

Makers 
Stockton,  Call 

PAT.  JAN.  21.  1908 


>ugges 
e  TO 
sun  on 


.ons   for  observ 
se   of  ti 
Janikary'l,   1889 


851037 


4  81 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


